The white matter of the brain is made up of billions of microscopic nerve fibers that pass information in the form of tiny electrical signals. To increase the speed at which these signals travel, each nerve fiber is encased by a sheath formed from a fatty substance, called myelin.

Previous studies have shown that the appearance of white matter in magnetic resonance images depends on the angle between the nerve fibers and the direction of the very strong magnetic field used in an MRI scanner.

Based on knowledge of the molecular structure of myelin, University of Nottingham physicists devised a new model in which the nerve fibers are represented as long thin hollow tubes with special (anisotropic) magnetic properties.

This model explains the dependence of image contrast on fiber orientation in white matter and potentially allows information about the nerve fibers—such as their size and direction—to be inferred from magnetic resonance images.

Research Fellow Samuel Wharton says, “While most MRI-based research focuses on tissue measurements at the millimeter length scale, our experimental scans on healthy human volunteers and modeling of the myelin sheath shows that much more detailed microscopic information relating to the size and direction of nerve fibers can be generated using fairly simple imaging techniques.

“The results will give clinicians more context in which to recognize and identify lesions or abnormalities in the brain and will also help them to tailor different types of scan to a particular patient.”

Nikolaos Evangelou, a clinical associate professor who specializes in multiple sclerosis at the Nottingham University Hospitals Trust says: “This research opens new avenues of looking at the nerve fibers in the brain. The more we understand about the nerves and the myelin around them, the more successful we are in studying brain diseases, such as multiple sclerosis.

“The recent advances in our understanding and treatments of MS are based on basic, solid research such as the one presented by Dr Wharton and Bowtell.”